A major question in the prevention of group B streptococcus type III (GBS) meningitis in humans is the efficacy of vaccination. Killed vaccines have not elicited good immune responses in both animal and human test groups. We have asked the question "Will maternal immunization with live organisms prevent disease in offspring following in-utero challenge 24 hours before delivery." Preliminary data indicates that vaccination with live organisms is efficacious in the rhesus monkey model. Several drug regimens were compared in the squirrel monkey model for the treatment of acute toxoplasmosis. The combination of pyrimethamine/sulfadiazine (PYR/SLD) or trimethoprim/sulfamethoxazole (TMP/SMZ) were equally effective in treating toxoplasmosis in the monkey model. TMP has been associated with fewer human toxic side effects than PYR. TMP has also been used in pregnant women without demonstrated teratogenic effect. It is available in an intravenous solution so that therapeutic blood levels can be quickly achieved. Controlled human studies of the use of TMP/SMZ in acute toxoplasmosis may be indicated.